13.14.5  The graphical representation of the area of a polygon: plotarea areaplot

The plotarea finds the (signed) area of a polygon.
areaplot is a synonym for plotarea.

• plotarea takes one argument:
  P, a polygon.
• plotarea(P) draws the filled polygon, with the signed area. (The area is positive if the polygon is counterclockwise, negative if it is clockwise.)

Examples.

• Input:
  plotarea(polygon(1,(1+i)/2,1+i)
  Output:
  
• Input:
  plotarea(polygon(1,1+i,(1+i)/2)
  Output:
  
• The fill color can be changed as a local feature (see 13.3.2) and the position of the legend can be changed (see 13.3.3).
  Input:
  plotarea(polygon(1,1+i,(1+i)/2),display=red+quadrant2)
  Output: